Study On Photocatalytic Degradation Of Formaldehyde In Indoor Air By Modified TiO₂

TiO₂ has attracted much attention as photocatalyst in the field of wastewater treatment for a long time.However,it just has notable photocatalytic activity under ultraviolet light because of its properties,and pure TiO₂ has shown a variety of deficiency such as low catalysis efficiency and long purification period in photocatalysis. Therefore,there is limitation in application.In order to improve its photocatalytic activity,and enlarge its application range by doping method,we synthesized titania particles doped with Ag,Cu,Fe,W,Ce,La,S,Cl respectively.To investigation on photo catalytic activity of the modified TiO₂,a series of experiments of photocatalytic decomposition of liquid and gas formaldehyde under exciting of ultraviolet light and visible light with the modified TiO₂ is conducted in this thesis respectively.The results show that photocatalytic property is governed by two major factors:existence condition of formaldehyde and light source.The gas condition and ultraviolet light excitation can contribute to its comparatively higher photocatalytic activity.The products doped with Cu,Fe,W,Ce,La can improve photocatalytic efficiency of formaldehyde,especially,titania particles doped with Cu has great effect on removing formaldehyde in the condition of gas atmosphere.They reached 60.6%and 55.32%under exciting of ultraviolet light respectively,and reached 56.7%and 35.58% under exciting of visible light respectively.The Titania particles doped with Cu and Ce are used as photocatalyst for photo degradation of formaldehyde in the environmental chamber that is fixed in 1m³.The results show that the concentration of formaldehyde is reduced to the nationalâ… type standard of construct materials by using TiO₂ doped with Cu and Ce within 9 hours and 10 hours respectively.By characterization of microstructure,it shows that doping modification of TiO₂ can not only promote growth of the TiO₂ particle,but also improve its photocatalytic activity.The surface area will reduce greatly with the growth of TiO₂ particle.It will lead to lower the photo catalytic activity.If the size of TiO₂ is controlled in the process of modification,photocatalytic activity would be improved greatly.